Lucene之删除索引-白红宇

Lucene之删除索引

阅读量：6854 次

发布时间：2019-06-26

本文共 8799 字，大约阅读时间需要 29 分钟。

1.前言

之前的博客《》已经简单介绍了Lucene的索引生成和检索。本文着重介绍Lucene的索引删除。

2.应用场景：

索引建立完成后，因为有些原因，被索引的文件已经删除。此时，索引仍然存在，为了不产生“虚假检索结果”，需要将失效的索引删除

3.HelloLucene类（重点关注deleteIndexByQuery方法）

package com.njupt.zhb;import java.io.BufferedReader;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStreamReader;import org.apache.lucene.analysis.Analyzer;import org.apache.lucene.analysis.standard.StandardAnalyzer;import org.apache.lucene.document.Document;import org.apache.lucene.document.Field;import org.apache.lucene.document.LongField;import org.apache.lucene.document.StringField;import org.apache.lucene.document.TextField;import org.apache.lucene.index.DirectoryReader;import org.apache.lucene.index.IndexReader;import org.apache.lucene.index.IndexWriter;import org.apache.lucene.index.IndexWriterConfig;import org.apache.lucene.index.IndexWriterConfig.OpenMode;import org.apache.lucene.index.Term;import org.apache.lucene.queryparser.classic.ParseException;import org.apache.lucene.queryparser.classic.QueryParser;import org.apache.lucene.search.IndexSearcher;import org.apache.lucene.search.Query;import org.apache.lucene.search.ScoreDoc;import org.apache.lucene.search.TopDocs;import org.apache.lucene.store.Directory;import org.apache.lucene.store.FSDirectory;import org.apache.lucene.util.Version;/* *@author: ZhengHaibo   *web:     http://blog.csdn.net/nuptboyzhb *mail:    zhb931706659@126.com *2013-08-27  Nanjing,njupt,China */public class HelloLucene {	/**	 * Index all text files under a directory.	 * String indexPath = "index";//索引保存的路径	 * String docsPath = "";//文档保存的路径（待索引）	 */	public void index(String indexPath,String docsPath) {		try {			// 1.创建Directory			Directory dir = FSDirectory.open(new File(indexPath));//保存在硬盘上			// 2.创建IndexWriter			Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_44);			IndexWriterConfig iwc = new IndexWriterConfig(Version.LUCENE_44,					analyzer);			iwc.setOpenMode(OpenMode.CREATE_OR_APPEND);// 设置创建或追加模式			IndexWriter writer = new IndexWriter(dir, iwc);			final File docDir = new File(docsPath);			indexDocs(writer, docDir);			writer.close();		} catch (IOException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}	}    	public void indexDocs(IndexWriter writer, File file) throws IOException {		if (file.canRead()) {			if (file.isDirectory()) {//如果是文件夹，则遍历文件夹内的所有文件				String[] files = file.list();				// an IO error could occur				if (files != null) {					for (int i = 0; i < files.length; i++) {						indexDocs(writer, new File(file, files[i]));					}				}			} else {//如果是文件				FileInputStream fis;				try {					fis = new FileInputStream(file);				} catch (FileNotFoundException fnfe) {					return;				}				try {					// 3.创建Document对象					Document doc = new Document();					// 4.为Document添加Field					// Add the path of the file as a field named "path". Use a					// field that is indexed (i.e. searchable), but don't					// tokenize					// the field into separate words and don't index term					// frequency					// or positional information:					//以文件的文件路径建立Field					Field pathField = new StringField("path", file.getPath(),Field.Store.YES);					doc.add(pathField);//添加到文档中					//以文件的名称建立索引域					doc.add( new StringField("filename", file.getName(),Field.Store.YES));//添加到文档中					// Add the last modified date of the file a field named					// "modified".					// Use a LongField that is indexed (i.e. efficiently					// filterable with					// NumericRangeFilter). This indexes to milli-second					// resolution, which					// is often too fine. You could instead create a number					// based on					// year/month/day/hour/minutes/seconds, down the resolution					// you require.					// For example the long value 2011021714 would mean					// February 17, 2011, 2-3 PM.					doc.add(new LongField("modified", file.lastModified(),Field.Store.YES));					// Add the contents of the file to a field named "contents".					// Specify a Reader,					// so that the text of the file is tokenized and indexed,					// but not stored.					// Note that FileReader expects the file to be in UTF-8					// encoding.					// If that's not the case searching for special characters					// will fail.					//以文件的内容建立索引域（Field）					doc.add(new TextField("contents", new BufferedReader(new InputStreamReader(fis, "UTF-8"))));					if (writer.getConfig().getOpenMode() == OpenMode.CREATE) {						// New index, so we just add the document (no old						// document can be there):						System.out.println("adding " + file);						writer.addDocument(doc);//将文档写入到索引中（以创建的方式）					} else {						// Existing index (an old copy of this document may have						// been indexed) so						// we use updateDocument instead to replace the old one						// matching the exact						// path, if present:						System.out.println("updating " + file);								writer.updateDocument(new Term("path", file.getPath()),doc);//以追加方式写入到索引中					}				} finally {					fis.close();				}			}		}	}	/**	 * 搜索	 * http://blog.csdn.net/nuptboyzhb	 */	public void searcher(String indexPath,String searchKeyword){		try {			IndexReader reader = DirectoryReader.open(FSDirectory.open(new File(indexPath)));			IndexSearcher searcher = new IndexSearcher(reader);			Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_44);			String field = "contents";//搜索域是：文档的内容			QueryParser parser = new QueryParser(Version.LUCENE_44, field, analyzer);		    Query query= parser.parse(searchKeyword);//搜索内容中含有searchKeyword字符串的文档		    TopDocs tds=searcher.search(query, 10);//搜索前十个		    ScoreDoc[] sds= tds.scoreDocs;		    for (ScoreDoc sd:sds) {//将内容中含有“南京”关键字的文档遍历一遍				Document document=searcher.doc(sd.doc);				System.out.println("score:"+sd.score+"--filename:"+document.get("filename")+						"--path:"+document.get("path")+"--time"+document.get("modified"));//打印检索结果中文档的路径			}		    reader.close();		} catch (IOException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}catch (ParseException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}	}	/**	 * 删除索引	 * @param indexPath 索引所在的路径	 * @param deleteKeyword 删除含有该内容的索引	 */	public void deleteIndexByQuery(String indexPath,String deleteKeyword){		try {			//1.新建一个IndexWrite			IndexWriter writer = new IndexWriter(FSDirectory.open(new File(indexPath)),new IndexWriterConfig(Version.LUCENE_44, new StandardAnalyzer(Version.LUCENE_44)));			//2.生成一个Query			Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_44);			String field = "contents";//搜索域是：文档的内容			QueryParser parser = new QueryParser(Version.LUCENE_44, field, analyzer);		    Query query= parser.parse(deleteKeyword);//生成搜索内容中含有deleteKeyword的文档			//3.按Query参数的方式删除索引，即删除了含有deleteKeyword的索引		    writer.deleteDocuments(query);		    writer.commit();//提交，正是删除		    writer.close();//关闭		    //		    //writer.deleteDocuments(new Term(field, ""));		}catch (IOException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}catch (ParseException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}	}}

4.编写Junit测试 类

package com.njupt.zhb;import org.junit.Test;/* *@author: ZhengHaibo   *web:     http://blog.csdn.net/nuptboyzhb *mail:    zhb931706659@126.com *2013-08-25  Nanjing,njupt,China */public class TestJunit {   @Test   public void TestIndex(){	   HelloLucene hLucene=new HelloLucene();	   hLucene.index("index", "D:\\lucene");   }   @Test   public void TestSearcher(){	   HelloLucene hLucene=new HelloLucene();	   hLucene.searcher("index","南京");   }   @Test   public void TestDeleteIndexByQuery(){	   HelloLucene hLucene=new HelloLucene();	   System.out.println("未删除前，查询关键字：北京  --结果：");	   hLucene.searcher("index","北京");	   hLucene.deleteIndexByQuery("index", "北京");	   System.out.println("删除后，查询关键字：北京  --结果：");	   hLucene.searcher("index","北京");   }}

5.实验结果

5.1运行TestIndex方法

>控制台打印的信息

updating D:\lucene\lucene1.txtupdating D:\lucene\lucene2.txtupdating D:\lucene\lucene3.txtupdating D:\lucene\北京.txtupdating D:\lucene\南京.txt

此时的index目录下的截图：

5.2运行TestSearcher方法

>搜索含有关键字“南京”的文档

score:0.53033006--filename:lucene3.txt--path:D:\lucene\lucene3.txt--time1376828819375score:0.48666292--filename:lucene2.txt--path:D:\lucene\lucene2.txt--time1376828783791score:0.2155931--filename:北京.txt--path:D:\lucene\北京.txt--time1377784223795score:0.1530931--filename:南京.txt--path:D:\lucene\南京.txt--time1377784261486

5.3运行TestDeleteIndexByQuery方法

未删除前，查询关键字：北京  --结果：score:0.4847152--filename:lucene2.txt--path:D:\lucene\lucene2.txt--time1376828783791score:0.39226472--filename:北京.txt--path:D:\lucene\北京.txt--time1377784223795score:0.10348864--filename:lucene3.txt--path:D:\lucene\lucene3.txt--time1376828819375score:0.029874597--filename:南京.txt--path:D:\lucene\南京.txt--time1377784261486删除后，查询关键字：北京  --结果：

删除后，再次查询关键字时，无查询结果。

此时，index目录下的文件结构为：